Stripper plate bolt assembly for a die set



R. E. HLAVAC. 3,418,839

TE BOLT ASSEMBL K 39 l I I v/ 47 45 Fig.

INVENTOR, Pm/420 E. HLAVAC BYW/ Ml Hm *M ATTORNEYS,

Dec. 31, 1968 R. E. HLAVAC STRIPPER PLATE BOLT ASSEMBLY FOR A DIE SET Sheet 2 of Filed Oct. 22. 1965 w 4 4 24 4 n F W W M, M

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INVENTOR. PIC/442D E. HLA vac ATTOPNEKE.

United States Patent 3,418,839 STRIPPER PLATE BOLT ASSEMBLY FOR A DIE SET Richard E. Hlavac, 25921 Yeoman Drive, Westlake, Ohio 44145 Filed Oct. 22, 1965, Ser. No. 501,919 2 Claims. (Cl. 72344) ABSTRACT OF THE DISCLOSURE A stripper bolt and a stripper bolt, die set and stripper plate assembly for a die press in which the stripper bolt has a shank, a round head with a projection extending laterally from the edge of said head, a flat end remote from said head, and a drilled and tapped hole for the reception of a fastening screw, the die set is drilled and bored complementarily to the stripper bolt and the stripper plate is held tight against said fiat end.

This invention relates to stripper plates and progressive die assemblies for stamping and drawing and more particularly to stripper bolts for holding and retaining a stripper plate on a die set punch holder, to a stripper bolt, stripper plate and die set assembly and to a process for making the same.

Stripper plates have long been used in punch press dies to strip the material being worked from cutting punches and the like. Recently, however, with the increased use of progressive dies, the stripper plates have been used to perform many other functions in addition to the traditional stripping operation. These additional functions include retaining forming inserts, forming cams and female die cavities, functioning as pressure devices for metal drawing and as guides for weak or thin punches, and for spanking or flattening parts.

As the functions performed by the stripper plate have increased, the need for greater vertical movement of and greater spring pressure behind the stripper plate has become increasingly mandatory. The dies themselves have also become larger. In the past, it has been customary, in practice, to mount the stripper plate on the die set by means of shoulder bolts extending through the die from the press ram side and screwing into the stripper plate and frequently the Springs have surrounded the shoulder bolts. Such structure has proven inconvenient in use because it necessitates removing the die set from the press ram in order to remove the stripper plate from the die set.

Yet during operation of the press, breakdowns, the need to change punches, and the like, and other difiiculties often require removal of the stripper plate. For these reasons, as well as to facilitate set up, it is desirable and advantageous to be able to quickly and easily remove the stripper from the die set and preferably to accomplish such removal without first requiring removal of the die set from the press ram.

Suggestions for structures permitting removal of the stripper plate from the die set without requiring prior removal of the die set have been made but none has proven satisfactory in practice and none has been widely adopted.

Thus, it is a general object of this invention to provide a new and improved stripper bolt for mounting stripper plates on die sets and the like, a new and improved stripper bolt, stripper plate and die set assembly, and a new and improved process for making said new and improved assembly.

Further objects of this invention include the provision of a new and improved stripper bolt and a new and improved stripper bolt, stripper plate and die set assembly which provides for removal of the stripper plate without requiring prior removal of the die set; which is easily and economically manufactured, used and installed; which is foolproof in operation and does not bind or otherwise in terfere with the operation of the press, even when press speeds are high and products formed thereon complicated; which is more economical to make and use than usual prior art practices; which may be used on existing presses; and, which is easily adjusted for use within the present practices as the same relate to die set structures and mountings.

Other objects of this invention include the provision of a new and improved process for making stripper bolt, stripper plate and die set assemblies which is easily and economically accomplished; which is safe in use and operation; and, which provides a new and improved stripper bolt, stripper plate and die set assembly and a new and improved ease and facility of using the same.

A still further object of this invention is to provide a new and improved stripper bolt, a new and improved stripper bolt, stripper plate and die set assembly and a new and improved process for making the same obtaining one or more of the objects and advantages set forth above.

These and other objects and advantages of this invention will appear from the following description of preferred forms thereof, reference being had to the attached drawings in which:

FIGURE 1 is a broken sectional view of a typical press showing a stripper bolt and a stripper bolt, stripper plate and die set assembly, embodying this invention;

FIGURE 2 is an elevational view, on an enlarged scale, of the stripper bolt shown in FIGURE 1;

FIGURE 3 is a top plan view of the bolt shown in FIGURE 2;

FIGURE 4 is a schematic, broken vertical sectional view illustrating the first step in the method of forming the stripper bolt cavity according to this invention;

FIGURE 5 is a top plan view of FIGURE 4;

FIGURE 6 is a schematic, broken vertical sectional view illustrating the second step in the method of forming the stripper bolt cavity according to this invention;

FIGURE 7 is a top plan view of FIGURE 6;

FIGURE 8 is a schematic, broken vertical section view illustrating the third step in the method of forming the stripper bolt cavity according to this invention; and,

FIGURE 9 is a top plan view of FIGURE 8.

FIGURE 1 depicts the structure of this invention in the environment of a typical press, set up for a progressive die bending station, in the closed position.

The press ram is shown at 1 and the bolster (fixed head) at 2. The lower die shoe 4 is mounted on the bolster 2 and the die steels 5 and 5' are mounted on the shoe 4 and hold, support and position the movable die pad 7, the die forming insert 8 and the stock guides 10 and 11, respectively. Stock guides 10 and 11 guide the stock 13, as the stock is progressed, in a fore and aft direction, as viewed, through the press. A spring 14, disposed in bore 16 in shoe 4, exerts pressure on pad 7 and disposes the pad to move or displaces it, in an upwardly direction, as viewed. Overlying or interlocking ears or flanges 17 and 19 on die steel 5 and pad 7, respectively, limit the upward vertical displacement of the pad 7 when the press is open.

Die set punch holder 20 is mounted on press ram 1 and supports and carries the stripper plate 22 and one or more punches and/or punch plates, 23 and 25, re spectively. A plurality of springs 26, one shown, are disposed between die set 20 and stripper plate 22, as in suitable seats or bores 28 and 29 in die set 20 and stripper plate 22, respectively. One or more stripper inserts 31 may be mounted on stripper plate 22 to aid in the forming operation.

The operation of the above described press is as follows: The press ram opens. The stock 13 advances at a level slightly above the forming insert 8 until the stock is advanced to its next position. The press ram 1 descends and the stock is gripped between the lower pad 7 and the stripper plate 22. Springs 26 acting upon stripper plate 22 create sufl'lcient pressure to overcome spring 14, thereby forcing pad 7 down, as viewed, and forming bend A between inserts 8 and 31. When pad 7 bottoms, stripper plate 22 deflects and punch 23 forms bend B. The ram then opens, lifting the die 20 and stripper plate 22 and associated assembly upwardly, as viewed, and the springs 26 displace the stripper plate downwardly, as viewed, relative to the die set, to force the stock 13 off the punch 23 and free the stock for the next advance, spring 14 simultaneously displacing pad 7 into its upward position, and the cycle is repeated, as desired.

All of the above is old and well-known in the art and, per se, forms no part of the present invention.

Stripper plate 22 is moved upwardly and downwardly with and as part of the press ram 1 and die set 20, as well as having upwardly and downwardly motion relative to and independent of the press ram and die set during the cyclical upward and downward movement thereof. In order to provide for and limit this relative movement between stripper plate 22 and die set 20 and to provide means whereby stripper plate 22 is easily and quickly detached and removed from the die set 20, without requiring removal of the die set from the press ram when adjustment, correction of error or breakdown, or replacement of a die or insert, etc., is required, all without binding or interfering with the movement and motion and relative motion of the stripper plate during operation of the press, a stripper bolt and assembly thereof with stripper plate 22 and die set 20 embodying this invention are provided, one shown and indicated generally at 35, FIG- URE 1. Stripper bolt assembly 35 includes stripper bolt 36, FIGURES 1, 2 and 3, having a shank 37, and a round head 38 with a projection or rib 39 extending a short distance from one side thereof. Projection 39 may have any desired shape, but in the preferred form of this invention is substantially semi-circular. Projection 39 functions, as will hereinafter more fully appear, to prevent bolt 36 from turning about its longitudinal axis. Bolt 36 also has a fiat end 40 remote from head 38 and is drilled and tapped, as at 41, at end 40 to receive an ordinary fastening screw 42, FIGURE 1, which may be of the ordinary Allen or similar type or flat-headed, if the stripper plate is thin.

In order to mount and support the stripper plate 22 on the die set 20, a bore 44, having a diameter having a close sliding fit with the shank 37 of bolt 36 is formed in die set 20, and is counterbored, as at 45, at the side set remote from the stripper plate, to a depth above the head of bolt 36 equal to the travel which the stripper plate is to have relative to the die set during the forming cycle. Counterbore 45 has a diameter such as to provide a smooth sliding or gliding fit with head 38 of bolt 36 and is provided at one edge with slot 47 having a size to receive projection 39 and a shape which is conveniently complementary thereto so that the projection 39 has a smooth sliding fit therewith.

The interengagement between the side of slot 47 and projection 39 prevents bolt 36 from rotating about its axis to and for the purpose to be hereinafter more fully described.

In addition, stripper plate 22 is bored, as at 48, in vertical alignment with bore 41, to receive the shank of screw 42, and bore 48 is 'counterbored, as at 50, remote from the die set 20, complementary to the head '51 of screw 42. Stripper plate 22 is mounted on the die set 20 by inserting the stripper bolt 36 into the bore 44 with bolt head 36 in counterbore 45 and projection 39 in slot 47. Bolt 36 extends below the die set 20 and the stripper plate is positioned thereunder with bore 48 in alignment with hole 41. Fastening screw 42 is then inserted through bore 48 and into engagement with the threads in hole 41 and tightened to hold the stripper plate tightly and firmly against the flat end 40 of bolt 36, with head 51 of screw 42 within counterbore 50. Further, the aforesaid interengagement between projection 39 and the side of slot 47 prevents bolt 36 and screw 42 from turning together, upon rotation of the screw 42, thereby insuring that the screw 42 may be easily tightened and loosened within and relative to bolt 36. Thus, the stripper plate 22 is easily and quickly positioned on and removed from die set 20.

Bore 44, counterbore 45 and slot 47 are easily and readily made, according to the method of this invention, for stripper bolts 36 embodying this invention and having the preferred form thereof with a round head 38 by first drilling bore 44 clear through die set 20, see FIG- URES 4 and 5. A round hole 47' having a circumference complementary to the projection 39 is then drilled in die set 20, in proper position relative the bore 44 to receive the projection 39, extending from head 38, in the completed assembly, see FIGURES 6 and 7. And finally the counterbore 45 is drilled in die set 20, see FIGURES 8 and 9.

Counterbore 45 is made with a standard counterboring tool to a depth equal to the length of the bolt head and the travel which the stripper plate will have relative to the die set.

Hole 47' is conveniently drilled to a deeper depth than the proposed depth of counterbore 45 so as to ensure proper depth and in view of the fact that excess depth is not critical, and, since the diameter and location of slot 47 is not critical, within the usual meaning in this art, hole 47 is conveniently and economically drilled as a simple drill press operation.

The height and diameter of the projection 39 is not critical, but it must be sufficient to prevent the bolt 36 from turning while screw 42 is tightened and loosened without breaking off or damaging the slot 47 and counterbore 45. Similarly, the top of head 38 can be indented to facilitate manufacture of projection 39 on head 38, as by cold rolling, etc., provided the head is not unduly weakened so as to interfere with the function, operation and purpose of the stripper bolt in accordance with teachings of this invention.

Modifications and changes to the preferred forms of the invention disclosed herein may occur to those skilled in the art who come to understand the principles and precepts thereof. Accordingly, the scope of the patent to be issued hereon should not be limited to the forms of the invention herein specifically depicted and described but by the advance by which the invention has promoted the art.

I claim:

1. A stripper bolt, die set, and stripper plate assembly for a die press, and the like, comprising a die set mounted on the press ram, a stripper plate and a stripper bolt, said stripper bolt having a shank, a round head, and a flat end remote from said head, a drilled and tapped hole extending inwardly from said flat end, and a semi-circular projection extending laterally from the edge of said head and having a length no longer than the length of said head and not extending axially beyond said head, a bore in said die set having a close sliding fit with said stripper bolt shank, a counterbore in said die set remote from said stripper plate and having a diameter having a close sliding fit with said bolt head and a depth greater than the axial length of said bolt head by the length of relative travel between said stripper plate and said die set, a slot on said counterbore having a shape complementary to said projection, said bolt being disposed with said shank in said bore, said head in said counterbore and said projection in said slot, said projection and the side of said slot inter-engaging to prevent said bolt from rotating about its longitudinal axis, a bore in said stripper plate in axial alignment with said drilled and tapped hole in said bolt, a counterbore in said stripper plate remote from said die set, and a fastening screw extending through said stripper plate bore and engaging in said drilled and tapped hole and coacting with said bolt to hold and support said stripper plate in position against said end of said stripper bolt, said fastening screw having a head drawn up tight in said stripping plate counterbore.

2, A stripper bolt, die set, and stripper plate assembly for a die press, and the like comprising a die set mounted on the press ram, a stripper plate and a stripper bolt, said stripper bolt having a shank, a round head, and a flat end remote from said head, a drilled and tapped hole extending inwardly from said fiat end, and a semi-circular projection extending laterally from the edge of said head, a bore in said die set having a close sliding fit with said stripper bolt shank, a counterbore in said die set remote from said stripper plate and having a diameter having a close sliding fit with said bolt head and a depth greater than the axial length of said bolt head by the length of relative travel between said stripper plate and said die set, a slot on said counterbore having a shape complementary to said projection, said bolt being disposed with said shank in said bore, said head in said counterbore and said projection in said slot, said projection and the side of said slot interengaging to prevent said bolt from rotating about its longitudinal axis, a bore in said stripper plate in axial alignment with said drilled and tapped hole in said bolt, a counterbore in said stripper plate remote from said die set, and a fastening screw extending through said stripper plate bore and engaging in said drilled and tapped hole and coacting with said bolt to hold and support said stripper plate in position against said end of said stripper bolt.

References Cited UNlTED STATES PATENTS 1,025,724 5/1912 Snyder 151-68 1,084,850 1/1914 Ford 85-4 1,683,501 9/1928 Tobeler 151-55 FOREIGN PATENTS 955,667 4/1967 Great Britain.

RICHARD J. HERBST, Primary Examiner.

US. Cl. X.R. 

